Retention of Extractable Beta Carotene from Asystasia Mysorensis and Solanum Nigrum Vegetables Palm Oils
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Date
2017
Authors
Muturi, Nderitu Samuel
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Publisher
Kenyatta University
Abstract
Hidden hunger, caused by lack of micronutrients in the diet afflicts billions of people especially in developing nations. Vitamin A deficiency (VAD) is among the top ten risk factors contributing to the global burden of disease, with WHO estimating 1.4 % of all deaths worldwide attributed to it. The deficiency can be addressed by intake of foods rich in preformed vitamin A such as eggs, meat or dairy products, however these are expensive and out of reach for the poor population. A suitable alternative would be vegetables which are rich in beta carotene (a provitamin A carotenoid) but they are seasonal, ignored or underutilized. In Kenya, indigenous vegetables Solanum nigrum and Asystasia mysorensis, though rich in beta carotene and locally available are grossly underutilized yet they can offer a solution to address VAD. The concern on the perishability of these vegetables calls for a cheaper way of preservation compared to conventional methods including refrigeration, canning and sun-drying. Despite numerous reports showing that oils increase bioavailability and bio-accessibility of beta carotene, no information is available on preservation of extractable beta carotene in edible oils. This study investigated the retention of beta carotene extracted from S. nigrum and A. mysorensis and preserved separately in sunflower and palm oils for a period of 180 days. The peroxide and acid values of the oils were determined by iodometric titration while RP-HPLC was employed for quantitative determination of beta carotene. One way ANOVA was used for data analysis while SNK was used for separation of means. The mean levels of beta carotene extracted from A. mysorensis and preserved in sunflower and palm oils reduced from 24.83 ± 0.002 to 6.67 ± 0.002 mg/100g DM (73.14 % decrease) and 24.82 ± 0.001 to 8.45 ± 0.001 (69.95 % decrease) respectively for the duration of 180 days. Levels of beta carotene from S. nigrum preserved in sunflower and palm oils reduced from 41.48 ± 0.003 to 7.65 ± 0.003 (81.56 % decrease) and 41.46 ± 0.003 to 14.28 ± 0.001 (65.56 % decrease) respectively for the same duration. This translates to 0.513 ± 0.0002, 0.650 ± 0.0001, 0.588 ± 0.0002 and 1.098 ± 0.0001 mg/100g DM of retinol activity equivalent (RAE) respectively at the end of storage duration. These values show considerable degradation of beta carotene in sunflower and palm oils though the final amounts retained provided more than the recommended daily allowance (RDA) of retinol in 100 mg consumed. Peroxide values in sunflower and palm oils increased from 3.93 ± 0.03 to 6.84 ± 0.04 and 2.00 ± 0.01 to 2.4 ± 0.01 mEq/kg oil respectively while acid values rose from 0.34 ± 0.01 to 0.64±0.04 and 0.11 ± 0.01 to 0.49 ± 0.04 mg KOH/g respectively. These values indicate that oxidation of the oil matrices occurs with time but not to critical levels (10 mEq/ kg oil and 0.6 mg KOH/g respectively) for the 28 days studied. The findings indicate that edible oils can preserve beta carotene if peroxide and acid values are kept at allowable levels.
Description
A Thesis Submitted in Partial Fulfillment of the Requirements for the Award of the Degree of Master of Science (Applied Analytical Chemistry) in the School of Pure and Applied Sciences of Kenyatta University. September, 2017